Wooden plug



Nov. 24, 1936.

...ww N" WOODEN PLUG Filed March 28, 1935 Patented Nov. 24, 1936 UNITED STATES many, assignor to Riit schaft, Berlin, German gerswerke-Aktie'ng'esell- Y Application March 28, 1935, Serial No. 13,561 In Germany February 20, 1934 The present invention relates to a plug, dowel, screw plug or such like acting as preservative for timbernf'any kind. The plug or the like, according to this invention, preferably consists of wood containing such a high percentage of water-soluble preservatives as has never been used before, and said plug or the like is used for inserting it in articial apertures, for instance bore holes in the wood. The preservative will then spread in dissolved form in the wood, thus causing a distribution of the preservative in the wood-without any further expedients-by diffusion or osmosis, as soon as the wood is suiiiciently moist. The Wooden plug or such like serves as carrier or receptacle for the preservative. The shape and the size of the plug or such like preferably must be adapted to shape and size of the apertures, so that the plug or the like will t tightly. Any kind of wood may be used for manufacturing these plugs or such like, for instance beech or pine, provided they can absorb the required amount of preservative. The use of hard wood is especially recommended, such as beech wood. However, in the place of wood it is also possible to employ suitable porous artificial substances,-such as porous artificial stone or the like-for the manufacture of plugs etc. The plugs and the like are impregnated with the preservative or its solution once or several' times, with or without application of pressure, at ordinary or raised temperature, for the purpose of introducing the required quantity of the preservative.

According to this invention the contents of Wood preservatives in the plug or the like is a multiple of the amount necessary to protect the impregnated wood permanently against attacks of Wood destroying organisms. While in the case of customary impregnation of wood suiiicient preservatives are introduced into the wood to prevent any attacks by woodpests and to provide a sucient store for balancing the loss sustained by lixiviation, evaporation or the like, according to the present invention a multiple of the previously used amount of wood preservative is accumulated in the plug or the like, since according to my invention the preservative contained in the plugs is to protect not only the plug itself but also the wood surrounding the plug.

In'carrying out my invention I employ preferably plugs which have been impregnated with an aqueous solution of potassium fluoride (KF). 100 parts of water at room temperature dissolve about 90 parts of potassium fluoride, so that very strong solutions may be prepared and used for impregnating. For example the wood vmay be' impregnated with a 30% aqueous solution of potassium fluoride. Furthermore, forexample'also magnesium uosilicate (MgSiF) may be used Which-is likewise readily soluble in water, or zinc fluosilicate (ZnSiFs). `I, have found that good results are obtained if the plug `or the like is saturated with strong solutions of such wood Y' preservatives which can be dissolved into soluf tions having a concentration of from .15% to e. g., of 20% or more, in Water at room temperature or higher temperature, for example at 70-80 C. It is also possible to use several substances, for examplev to impregnate the plugs etc. with vthe solution of several compounds, preferably drying the wood between the. individual impregnating operations. The impregnation with the aqueous solutions preferably .takes `place according to the so-called full-cell process. The

preservatives used may be inorganic or organic L compounds or mixtures of same. In addition to can enter the wood more easily, thus facilitating the distribution of Water-soluble substances.

The impregnated plugs or the like may be subsequently treated with oil, Asuch as tar oil, by

dipping them into the hot tar oil. This does not prevent the dissolution and the distribution vof the preservative and sometimes facilitates the insertion of the plugs.

It is essential for the present invention that sufcient amounts of preservatives are introduced into the plugs or the like. As above mentioned, it is necessary to introduce into the plugs or the like a multiple of the amount of preservative used in the ordinary impregnating processes against wood pests. Fo-r instance, plugs made of red beech may be incorporated with 50-200 kilos of potassium fluoride per. cubic meter by, for in'- stance, the full cell process. However, my invention is not limited to such proportions. P reservatives which are not only soluble in Water but also in other solvents may be used for impregnatingplugs after having been dissolved in such solvents. For example, corrosive sublimate ma'y be dissolved in alcohol and the plugs or the like are then impregnated with the solution obtained. The impregnation of the plugs may also be carried out with the aid of molten substances.

into the wood considerablequantities of preservatives and to distribute them in the wood without applying pressure or further expedients. l

The invention is illustrated in the accompanying drawing, wherein- Fig. 1 represents an embodiment in which a solid plug is employed, while f Fig. 2 represents another embodiment in which a hollow "plug is used.

In the drawing, the numeral I represents rthe block or article of wood to betreated, while 2 represents the solid plug impregnated with the preserving substance. In Fig. 2, the plug, which in this form is hollow or provided with a bore, is

indicated by the reference character 2', while the preservative substance with which the bore is illed is indicated at 3.

What I claim is: i l. Process for distributing water-soluble preservatives in wood', comprisingintroducing into the wood plugs, dowels, screw plugs or the like in which such proportions of water-soluble preservatives are stored as exceed by several times the amount required for the permanent protection of the wooden plug itself against wood destroying pests.

2. Process for distributing water-soluble preservatives in wood. as defined in claim 1, in which the wood plugs contain the water-soluble preservatives in concentrations yielding solutionsoi' a concentration oi' at least 20%.

3. Process for distributing water-soluble preservatives in wood, comprising introducing into the wood plugs, dowels, screw plugs or the vlike which have been saturated with an aqueous solution of from 15% to 50% of potassium fluoride according to the full-cell process.

NATHANAEL 'ZWINGAUER 

